This paper evaluates the impact of farmer field schools, an intensive participatory training program emphasizing integrated pest management. The evaluation focuses on whether program participation has improved yields and reduced pesticide use among graduates and their neighbors who may have gained knowledge from graduates through informal communications. The study utilizes panel data covering 1991–99 in Indonesia. The analysis, employing a modified “difference-in-differences” model, indicates that the program did not have significant impacts on the performance of graduates and their neighbors. Several plausible explanations for this outcome are discussed, and recommendations for improvements are suggested.